Bacteriological Changes in Silage Made at Controlled Temperatures

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Abstract
SUMMARY: Silage made in the laboratory at 22°, 30° and 40° from five specimens of grass was examined after 1, 2, 3 and 8 days and 6 months. The dominant bacteria on fresh grass were obligate aerobes which died rapidly in a closed silo. Bacteria capable of anaerobic growth were represented irregularly and often weakly on grass. This can account for much of the variation in the composition of bacterial populations in silage. Organisms that developed extensively in much of the silage were the Klebsiella group, Lactobacillus, Streptococcus, Leuconostoc, Pediococcus, Clostridium and Bacillus. Each proceeded to multiply soon after silos were closed; all stopped growing at about the same time. The rate of growth and the concentration of viable organisms reached were determined by properties of the herbage. Gram-negative organisms were restrained at 40°, Clostridium and Bacillus at 22°. The multiplication phase was short; it could be completed by the third day at all three temperatures. Cessation of growth could not be attributed to the accumulation of acids. Much acid was formed after all the main groups had reached the phase of decreasing viable count. When the lactic acid fermentation was not vigorous the decreases in pH value were most rapid at 40° and slowest at 22°.